Cache non-interactive find results in distdir

Language/Haskell/GhcMod/Find.hs

@@ -56,7 +56,8 @@ import Data.Map (Map)
 import qualified Data.Map as M
 import Data.Set (Set)
 import qualified Data.Set as S
-
+import Language.Haskell.GhcMod.PathsAndFiles
+import System.Directory
 import Prelude
 
 ----------------------------------------------------------------
@@ -83,7 +84,7 @@ isOutdated db =
 -- | Looking up 'SymbolDb' with 'Symbol' to \['ModuleString'\]
 --   which will be concatenated. 'loadSymbolDb' is called internally.
 findSymbol :: IOish m => String -> GhcModT m String
-findSymbol sym = loadSymbolDb >>= lookupSymbol sym
+findSymbol sym = loadSymbolDb' >>= lookupSymbol sym
 
 -- | Looking up 'SymbolDb' with 'Symbol' to \['ModuleString'\]
 --   which will be concatenated.
@@ -95,6 +96,21 @@ lookupSym sym db = map (ModuleString . unpackFS . mkFastStringByteString') $ S.t
 
 ---------------------------------------------------------------
 
+loadSymbolDb' :: IOish m => GhcModT m SymbolDb
+loadSymbolDb' = do
+  cache <- symbolCache <$> cradle
+  let doLoad True = do
+        db <- decode <$> liftIO (LBS.readFile cache)
+        outdated <- isOutdated db
+        if outdated
+        then doLoad False
+        else return db
+      doLoad False = do
+        db <- loadSymbolDb
+        liftIO $ LBS.writeFile cache $ encode db
+        return db
+  doLoad =<< liftIO (doesFileExist cache)
+
 -- | Loading a file and creates 'SymbolDb'.
 loadSymbolDb :: IOish m => GhcModT m SymbolDb
 loadSymbolDb = do

Language/Haskell/GhcMod/PathsAndFiles.hs

@@ -220,7 +220,7 @@ packageCache = "package.cache"
 
 -- | Filename of the symbol table cache file.
 symbolCache :: Cradle -> FilePath
-symbolCache crdl = cradleTempDir crdl </> symbolCacheFile
+symbolCache crdl = cradleRootDir crdl </> cradleDistDir crdl </> symbolCacheFile
 
 symbolCacheFile :: String
 symbolCacheFile = "ghc-mod.symbol-cache"